The present application relates to a bioassay substrate for detecting interactions between substances. More specifically, the application relates to a bioassay substrate in which a sample solution is dripped onto a spot area to which a plurality of detection substances is fixed and interactions between the detection substance and a target substance in the sample solution is detected by fluorescent intensity, and a bioassay method using the substrate.
In recent years, in the fields of making drugs, clinical diagnosis, pharmacological genomics, forensic medicine, and so on, a bioassay substrate such as a DNA chip (or DNA microarray) and a protein chip is starting to be used for the analysis of gene variations, the analysis of SNPs (a single nucleotide polymorphism), the analysis of gene expression frequency, and the analysis of the interaction between substances.
Generally, on a bioassay substrate, a plurality of wells is provided in advance which is the site for interaction (such as hybridization), and a target detection substance (such as a probe nucleic acid) is fixed to every well. Then, a sample solution is dripped onto each of the wells, an interaction between the detection substance and a target substance contained in the sample is developed, and then the interaction is detected by fluorescent intensity, whereby exhaustive analysis is conducted.
In addition, as a preceding reference having the relevance to the application, for example, Patent Reference 1 (see JP-A-2003-107086) is exemplified. The Patent Reference 1 discloses a technique in which a frosted surface with nearly uniform micro portions is formed in an area for solidifying a nucleic acid probe to enhance detection accuracy.
In the case in which a detection substance is fixed to a substrate surface, it is necessary to fix it in a single layer. Thus, the amount of a detection substance fixable in a well is restricted. Therefore, the amount of interaction between the detection substance and the target substance is also restricted, which causes a problem that when a bioassay substrate is used to detect the interaction between the detection substance and the target substance, it is difficult to obtain a sufficient detected amount (such as fluorescent intensity).
In addition, when a related art bioassay substrate is used to detect the interaction between the detection substance and the target substance, the detection accuracy and the signal-to-noise ratio is not always enough.